Organic molecules having two non-conjugated bridges between a donor and an acceptor for effective thermally activated delayed fluorescence for use in optoelectronic devices

ABSTRACT

The invention relates to purely organic emitter molecules of a new type according to formula I and to the use thereof in optoelectronic devices, in particular in organic light-emitting diodes (OLEDs), comprising donor D: an aromatic or heteraromatic chemical group on which the HOMO is located and which optionally has at least one substitution; acceptor A: an aromatic or heteromatic chemical group on which the LUMO is located and which optionally has at least one substitution; bridge B1, bridge B2: organic groups that link the donor D and the acceptor A in a non-conjugated manner; wherein in particular the energy difference ΔE(S 1 −T 1 ) between the lowest excited singlet (S1) state of the organic emitter molecule and the triplet (T1) state of the organic emitter molecule lying thereunder is less than 2000 cm −1 .

The present invention relates to organic molecules used foroptoelectronic devices and optoelectronic devices containing suchorganic molecules. The organic molecule has a donor unit and an acceptorunit, and the spatial positions of the donor unit and acceptor unit arelinked to each other by two organic non-conjugated bridges. The organicmolecules have a singlet state-triplet state narrow band gap required toeffectively delay fluorescence, making the molecule particularlysuitable for optoelectronic devices.

ABSTRACT

The invention relates to purely organic emitter molecules of a new typeaccording to formula I and to the use thereof in optoelectronic devices,in particular in organic light-emitting diodes (OLEDs), comprising donorD: an aromatic or heteraromatic chemical group on which the HOMO islocated and which optionally has at least one substitution; acceptor A:an aromatic or heteromatic chemical group on which the LUMO is locatedand which optionally has at least one substitution; bridge B1, bridgeB2: organic groups that link the donor D and the acceptor A in anon-conjugated manner; wherein in particular the energy differenceΔE(S₁−T₁) between the lowest excited singlet (S1) state of the organicemitter molecule and the triplet (T1) state of the organic emittermolecule lying thereunder is less than 2000 cm⁻¹.

BACKGROUND ART

For many optoelectronic applications, luminescent molecules(=emittermolecules) should have an emission decay time τ that is as short aspossible and a high photoluminescence quantum efficiency Ø_(L). Inaddition, during the emission process, the applications of moleculeswithout a metal complex, such as the inclusion of electrons in thelowest-excited triplet state T1 and the use of pure organic emittermolecules, are of great significance. Thermally-activated delayedfluorescence (TADF) can be generated at room temperature by setting asufficiently small energy difference ΔE (S₁−T₁) between the T1 state andthe singlet state S₁ above it (FIG. 1) to meet the stated requirements.This process is known to those skilled in the art (refer to, forexample, A. Parker, C. G. Hatchard; Trans. Faraday, Royal Society ofChem. 1961, 57, 1894), also called frequency boosting based on E type(because found firstly in eosin). As a result, it is possible to achieveeffective TADF, that is, a decay time (TADF) of the emission decreasesby several orders of magnitude compared to the phosphorescence decaytime τ (T₁) when a long-lived triplet state is involved. In addition,significant increase in emission quantum efficiency Ø_(PL) can beachieved in many cases, because the rapid return of competition occupiesthe process T₁→k_(B)T→S₁, reducing the non-radiative process of the T₁state (shown by the wavy lines in FIG. 1).

It is known from the prior art that, for many molecules with atransition in charge (CT) between the donor (D) fragment and thereceptor (A) fragment, TADF may occur. However, the energy differenceΔE(S₁−T₁) found to date is still obviously large, therefore,photophysical properties desired by many applications, such as shortdecay time τ(TADF), have not been achieved yet.

SUMMARY OF THE INVENTION

Surprisingly, it is possible to find a method (molecular structureprinciple) which helps to reduce energy difference ΔE (S₁−T₁) in atargeted manner to provide the corresponding pure organic molecules.According to equation (1), the energy difference is approximatelyproportional to the exchange integral of the quantum mechanics,

ΔE(S ₁ −T ₁)≈const.<ΨD(r ₁)ΨA*(r ₂)|r ₁₂ ⁻¹ |ΨD(r ₂)ΨA*(r ₁)>  (1)

Here, r₁ and r₂ are the electronic coordinates, and r₁₂ is the distancebetween the electron 1 and the electron 2. Ψ_(D) is the wave function ofthe HOMO (highest occupied molecular orbit). For this type of molecules,HOMO is mainly distributed in the donor portion (D) of the molecule,while Ψ_(A)* represents LUMO (lowest unoccupied molecular orbit), mainlydistributed in the receptor portion (A) of molecule. According to theequation (1), if the product Ψ_(D)(r₁)Ψ_(A)*(r₂) of wave functionbecomes small, ΔE (S₁−T₁) becomes small. This requirement is not reachedfor a variety of molecules with intramolecular CT transitions, becausethe spatial expansion of the wave function Ψ_(D)(r₁) and the excessiveoverlap of ΨA*(r₂) result in excessively large ΔE(S₁−T₁) value.According to the invention, a molecular structure having significantlyreduced wave function superimposition is proposed. This is achieved by amolecular structure in which non-conjugated, small chemical groups(bridges) separate donor and acceptor moieties, thus, significantlyreducing expansion of HOMO into the receptor area and expansion of LUMOinto the donor region.

The formula I shows the molecular structure of the organic moleculesaccording to the invention. There are two organic bridges between thedonor and acceptor fragments. By appropriatetly selecting these bridges,the spatial superposition of HOMO (mainly on the donor) and LUMO (mainlyon the acceptor) can be significantly reduced. In order not to make thetransition probability between the electronic ground state S₀ and theexcited state S₁ too small, slight overlap of the rails is of greatsignificance. In addition, double bridging causes the molecules toharden, achieving an increase of emission quantum efficiency and adecrease of half-value width of emission. In many cases, the decrease ofhalf-value width of emission is of great significance to acquire adefinite emtting color (color purity), for example, luminescence inOLEDs.

The formula I shows the molecular structure of one embodiment of anorganic molecule with two chemical bridges according to the presentinvention. These bridges significantly reduce the conjugation between Dand A and the overlap of HOMO and LUMO and stabilize the molecularstructure.

Formula I: it represents the molecular structure of an organic moleculeaccording to the invention. The organic molecule consists of an aromaticor heteroaromatic donor fragment D and an aromatic or heteroaromaticreceptor fragment A bound by two unconjugated bridges B1 and B2. Thebridges reduce the apparent overlap between the donor-HOMO and theacceptor-LUMO.

For optoelectronic applications that require a small value of ΔE(S₁−T₁), it is important that fragments D and A each have a sufficientlyhigh donor or acceptor intensity. (These terms are well known to thoseskilled in the art.) The corresponding intensity can be described by theintensity of the electron donating (for the donor) or the intensity ofelectron withdrawing (for the receptor).

By choosing the appropriate molecular structure, the energy differenceΔE (S₁−T₁) value can be made to be less than 2,000 cm⁻¹, in particularless than 1,500 cm⁻¹ or preferably less than 800 cm⁻¹ or even morepreferably less than 400 cm⁻¹ or in particular less than 200 cm⁻¹. Thecorresponding value is determined by a single molecule. The value can bedetermined by different methods.

The value of ΔE (S₁−T₁) is calculated from quantum mechanics, forexample, using a commercially available TD-DFT program (e.g. Gaussian 09program) or a free version of NWChem (e.g. version 6.1), CC2 method(TURBOMOLE GmbH, Karlsruhe) or CAS methods (complete active statemethod). (refer to D. I. Lyakh, M. Musiaz, V. F. Lotrich, R. J.Bartlett, Chem. Rev. 2012, 112, 182-243 and P. G. Szalay, T. Muller, G.Gidofalvi, H. Lischka, R. Shepard, Chem. Rev. 2012, 112, 108-181). Anexample of calculation is given in the embodiments.

ΔE (S₁−T₁) value can also be determined experimentally. The organicmolecules according to the present invention exhibit not onlyinstantaneous (=spontaneous) fluorescence components (decay time:several to dozens of nanoseconds), but also exhibit TADF attenuationcomponents with attenuation ranging from one hundred to several hundred.A commercially available device can be used to determine the relevantdecay time as a temperature function. By using the equation (2), theΔE(S₁−T₁) value can be determined by fitting the experimental curveaccording to the temperature change of the emission decay time [referto, for example, Czerwieniec R., Kowalski K., Yersin H.; Dalton Trans.2013, 42, 9826]:

$\begin{matrix}{{\tau (t)} = \frac{3 + {\exp \left( {{- \Delta}\; {{E\left( {S_{1} - T_{1}} \right)}/k_{B}}T} \right)}}{{3/{\tau \left( T_{1} \right)}} + {{1/{\tau \left( S_{1} \right)}}{\exp \left( {{- \Delta}\; {{E\left( {S_{1} - T_{1}} \right)}/k_{B}}T} \right)}}}} & (2)\end{matrix}$

Here, τ(T) is experimentally determined and, if necessary, it is theaverage decay time after instantaneous emission decay and thermalequilibrium (several hundred nanoseconds). τ(S₁) is the emission decaytime in the S₁ state. Other parameters have been defined earlier.

For many applications, the luminous decay time τ(TADF) (=τ(300K)) shouldbe as small as possible (as small as less than hundreds of μs). In orderto achieve this, it is significant to increase the spin-orbit-couple(SBK) effect between the T1 state and the higher molecular energy state,in addition to setting a small ΔE (S₁−T₁) value for obtaining greaterintersystem crossing rate (ISC). For this purpose, the donor fragment Dand/or acceptor fragment A can be replaced, for example, with halogenCl, Br and/or I.

For the molecules of the present invention, an intersystem crossing jump(ISC) rate can be increased. The molecules in the invention havelocalized states with energies very close to the CT state at donor Dand/or acceptor A. (In the case of a local triplet state where theenergy is lower than the charge transfer (CT) state, the number of thetriplet state changes, for example, the local state is called T1 and theCT-state is called T2). The rate is increased due to SBK enhancementbased on quantum mechanics mixing between these states. The targetmolecule is identified using known computer programs or quantummechanical methods (eg, Gaussian 09 or CC2 methods). The energy gapbetween the above states is less than 2000 cm⁻¹, in particular less than1500 cm⁻¹, more preferably less than 1000 cm⁻¹, further more preferablyless than 400 cm⁻¹ and most preferably less than 200 cm⁻¹. Mutual energyshifts can be achieved by changing the donor and/or acceptor intensityand changing electron donating substitution of donors and/or changingthe electron withdrawing substitution of acceptors. Energy shifts canalso be achieved by more than one substitutions of electron donatingand/or electron withdrawing. The CT state shift can also be achieved bychanging the polarity of the environment (e.g. polymer matrix).

The chemical bridges B1 and B2 between segments D and A not only havethe effect of enhancing the rigidity of the molecules, but alsosurprisingly increase the emission quantum efficiency Ø_(L).

In addition, these bridges strongly restrict the free migration of donormolecule fragment D relative to acceptor molecule fragment A. Thus, thevariation of the ΔE(S₁−T₁) value for a given emitter moleculeincorporated into the polymer matrix, i.e., the non-uniformity of thisvalue, is greatly limited, thereby significantly reducing the longemission decay time in the long-life “decay tail” area often occurringin the prior art. In addition, the color purity of the emission isimproved by reducing the half width of the emission band.

Description of Receptor a and Donor D in Formula I

The emitter molecule of Formula I consists of two fragments covalentlylinked by two bridges B1, B2, i.e. donor fragment D and acceptorfragment A. The donor fragment and acceptor fragment are composed ofaromatic or heteraromatic groups, or other alternatives. The bridges B1,B2 are short aliphatic or heteroaliphatic segments that greatly reducethe conjugation (delocalization) between the aromatic segments A and D.

The chemical structures of the molecular fragments A and D are describedin combination with the formulas II and III.

Formulas II and III: Structures of D and A molecular fragments. Thedonor and acceptor fragments consist of differentaromatic/heteroaromatic fragments, which, independently of one another,can be five- or six-membered ring systems, and can be substituted orexpanded (with Fused Aromatic Ring). The donor or acceptor fragments canbe obtained depending on the individual structure.

# marked site. The donor moiety D or acceptor moiety A binds to B1 andB2 via this site. The connotations of groups X1 to X7 and Y1 to Y4 willbe explained below.

Y1, Y2, Y3 and Y4 are C or N, independently of each other.

X1 to X7 are N, O, S, Se, CH, NH, C—R1 or N—R2, independently of eachother. Wherein R1 and R2 groups are independently selected from —H,alkyl (e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, adamantyl), cycloalkyi (e.g. cyclopropyl, cyclopentyl,cyclohexyl), alkenyl (e.g. vinyl, allyl), alkynyl (e.g. ethynyl), aryl(e.g. phenyl, tolyl, naphthyl), heteroaryl (e.g. furyl, thienyl,pyrrolyl), chemically substituted alkyl, alkenyl, alkynyl, aryl, orheteroaryl, alkoxy (—OR′), thioalkyl (—SR′), sulfonyl (—SO2R), acyl(—COR′), formyl (—CHO), carboxyl (—CO2R′), boryl (—BR′R″), sulfinyl(—SOR′), amine (—NR′R″), phosphino (—PR′R″), phosphinyl (—POR′R″), amido(—NR′COR), silyl (—SiR′R″R′), cyano and (—CN), nitro (—NO2), nitroso(—NO), isocyanato (—NCO), thiocyano (—NCS) or halogen (—F, —Cl, —Br,—I). The residues R′, R″ and R′″ are defined as R1 and R2. The residuesR′, R″ and R′″ can be covalently linked to each other, so thataliphatic, heteroaliphatic or unsaturated ring systems can also beformed.

In addition, the group R1 or R2 can be alkyl-C_(n)H_(n+1) (1≤n≤8,particularly 1≤n≤4), cycloalkyl-C_(n)H2_(n−1) (3≤n≤6), substitutedalkyl/cycloalkyl, alkoxy-OC_(n)H_(2n+1) (1≤n≤8, particularly 1≤n≤4),thioalkyl-SC_(n)H2_(n+1) (1≤n≤8, particularly 1≤n≤4), or alkylated aminegroups, —N(C_(n)H_(2n+1))(C_(n′)H_(2n′+1)) (n and n′=1 to 8,particularly 1, 2, 3) or —N(C_(n″)H2_(n″−1))(C_(n)′″H2_(n′″−1)) (n″ andn′″=3, 4, 5 or 6, particularly 5 or 6).

The pendant groups (R1 and R2) of fragments X1 to X3 or X4 to X7 of therespective molecular moiety (donor D, acceptor A) can be linked togetherin such a way as to form other aliphatic, aromatic or (hetero) aromaticring systems.

Some embodiments of the molecules according to the invention have tworing systems of the formula II or two ring systems of the formula III,which may be the same or different. If the ring systems are the same,these ring systems have different substitution patterns.

In a specific embodiment, the aromatic or heteroaromatic rings belongingto the donor and acceptor segments linked by two bridges B1, B2 are notfused with other aromatic or heteroaromatic rings; in this embodiment,donor fragment d and receptor fragment A have only one aromatic orheteroaromatic ring respectively.

In one embodiment of the invention, in order to increase spin-orbitcoupling, the bridges of aromatic and/or heteroaromatic ring systems ororganic molecules with halogen (Cl, Br or I).

Molecular systems according to Formula II (five-membered ring system)and Formula III (six-membered ring system) can effectively act as donorsor acceptors. In order to achieve a specific donor effect, the HOMO mustbe electron-rich zone and mainly located on the donor moiety. In orderto achieve a specific receptor effect, LUMO must be electron-deficientzone and mainly located on the acceptor moiety. The orbital schematicshown in FIG. 2 should illustrate the energy preconditions for achievinga D-A-emitter molecule according to the present invention.

Generally, the HOMO and LUMO energies of the respective donor andacceptor moieties can be determined electrochemically. In order torealize the substance having the orbital characteristics as shown inFIG. 2, the following conditions must be satisfied: (1) the oxidationpotential of the donor fragment is smaller than the oxidation potentialof the acceptor fragment: E_(OX)(D)<E_(OX)(A)(E_(OX)=oxidationpotential), (2) the reduction potential of the receptor fragment isgreater than the reduction potential of the donor fragment:E_(RED)(D)<E_(RED)(A)(E_(RED)=reduction potential). The redox propertiesof many conventional aromatics can be available from the followingreferences[[M. Montalti, A. Credi, L. Prodi, M. T. Gandolfi, Handbook ofPhotochemistry, 3rd ed., CRC Tayler & Francis, Boca Raton, 2006].Correspondingly, electron-excited states occur in donor-acceptormolecules, which are characterized by a marked shift of the electrondensity from the donor to the acceptor as compared to the molecules ofthe ground state (S₀). This state is called Charge Transfer (CT) state.As is well known to those skilled in the art, this results in theexcitation singlet state ¹CT (corresponding to the S₁ state as definedabove) and the excitation triplet state ³CT (corresponding to the T₁state as defined above).

Electron-rich donor fragments or electron-deficient acceptor fragmentscan be achieved by introducing specific heteroatoms into the fused ringsystem and/or by performing specific substitutions with electrondonating or electron withdrawing functional groups. Therefore,introducing heteroatoms, typically nitrogen (forming aza-aromatics) inaromatic six-membered rings will affect the stability of the π and π*orbitals based on the mediation effect known to those skilled in theart. As a result, the mono-electron reduction and oxidation potentialsof the azaaromatics are higher than the redox potentials of thecorresponding pure aromatic (non-heteroatom) hydrocarbons. In thearomatic five-membered system, the introduction of heteroatoms, usuallynitrogen, destabilizes the π and π* orbitals through the mesomericeffect, resulting in lower oxidation and reduction potentials.Additional orbital energy modulation is achieved by either electronwithdrawing (EWG=electron withdrawing group) or electron donating(EDG=electron donating group) functional groups. EWG substitutionsgenerally result in lower HOMO and LUMO energies, whereas EDGsubstitutions generally result in higher HOMO and LUMO states. Generallythe following EWG or EDG are used: [M. Smith, J. March; March's AdvancedOrganic Chemistry, Reaction, Mechanism and Structure, 6th ed. John Wiley& Sons, Inc., Hoboken, N.J., 2007]

EDG Example:

—NR′R″, —NHR′, —OR′, -alkyl, —NH(CO)R′, —O(CO)R′, -(hetero)aryl,—(CH)CR′R″, phenoxazinyl, phenothiazinyl, carbazolyl,dihydrophenylhydrazinyl, all aryl and heterocyclic groups may optionallybe substituted by other alkyl and/or aryl groups and/or F, Cl, Br and/orI. (If necessary, apply to increase SBK). R′ and R″ are defined asabove.

For selected EDG substitutions, it is also possible to determine thedonor intensity (EDG intensity) arrangement:

Strong-intensity electron donors: —O⁻, —N(CH₃)₂, —N(C₆H₅)₂,phenoxazinyl, phenothiazinyl, carbazolyl, —NHCH₃;

Medium-intensity electron donors: —OC₆H₅, —OCH₃, —NH(CO)CH₃;

Weak-intensity electron donors: aryl, —C(CH₃)₃, —CH₃.

EWG Example:

Halogen, —COR′, —CO₂R, —CF₃, —BR′R″, —BF₂, —CN, —SO₃R, —NH₃ ⁺,—(NR′R″R′″)⁺, alkyl group. R′, R″ and R″ are defined as above.

For selected EWG substitutions, the acceptor intensity (EWG intensity)arrangement can be given:

Strong electron-withdrawing: —NO₂, —CF₃, —CH(CN)₂, —CN;

Medium electron-withdrawing: —SO₃CH₃, —COCH₃, —CHO; —F

Weak electron-withdrawing: —Cl, —Br, —I. (If necessary, apply toincrease SBK).

In one embodiment, the donor fragment D is selected from substitutedaromatic five-membered rings or substituted aromatic six-membered rings,wherein the five- and/or six-membered rings have at least one electrondonating substituents (EDG) (pendant group at X1 to X3 or X4 to X7)and/or have one or more heteroatoms such as Y1, Y2, X1, X2, or X3=N in afive-membered ring system. It is also preferred to use at least one EDGfor substitution if the pendant group linkage at X1, X2 and X3 or X5, X6and X7 results in the condensation system expanding to an additionalaromatic ring.

In one embodiment, the acceptor fragment A is selected from substitutedaromatic five-membered rings or substituted aromatic six-membered rings,wherein the five- and/or six-membered rings have at least one electronwithdrawing substituents (EDG) (pendant group at X1 to X3 or X4 to X7)and/or have one or more heteroatoms such as Y3, Y4, X4, X5, X6 or X7=Nin a six-membered ring system. It is also preferred to use at least oneEWG for substitution if the pendant group linkage at X1, X2 and X3 orX4, X5, X6 and X7 results in expanding to an additional aromatic ring.

As described above, both the donor fragment D and acceptor fragment Amay have fused rings. The number of donor and/or acceptor conjugatedrings is less than four. In ring systems with a conjugate ring numbergreater than 1 (but less than or equal to 3), it may be necessary tochoose substitutions that have stronger electron-withdrawing effects onthe donor fragments and/or have stronger electron-withdrawing effects onthe acceptor fragments.

In one embodiment, bridges B1 and B2 have a structure as defined byformulas IV and V, wherein the bridges B1 and B2 may be the same ordifferent.

The symbol # indicates the linkage with the molecule donor or acceptormoiety. A1 to A3 represent fragments of bridges B1 and B2, wherein thefragment of the bridges B1 and B2 with the same name can be same ordifferent.

Chemical group A1 is:

O, S or

wherein the chemical groups R3-R7 are defined as above R1 and R2.

Chemical groups A2 and A3 are:

A2:

O, S or

A3:

O, S or

In addition, one or more groups of A2 and A3 may be one of the followinggroups independently,

Groups R8 to R22 are defined as R1 and R2.

It is achieved to bridge the donor or acceptor via the atoms selectedfrom C, N, Si, O, S, P, B and Ge, and the interconnection in thepresence of multiple bridge elements A2 and A3 (Formula V).

DETAILED DESCRIPTIONS OF EMBODIMENTS

The molecular structure of the emitter material having the formula Iaccording to the invention is further explained by means of thestructural formulas VI to XVII. These structural formulas representexamples of emitter materials according to the invention. Y1′-Y4′ andX1′-X7′ are defined as Y1-Y4 and XI-X7 (formulas II and III). A1′, A2′,A3′ groups are defined as A1 to A3. The bridge fragments A1 and A1′, A2and A2′, A3 and A3′, respectively, may be the same or different.

Additional bridging groups Z are, for example, —CH₂—, —C(CH₃)₂, —O—,—C₆H₄-(phenylene), —C₅H₈-(cyclopentylene), —CO-(carbonyl), —SO₂—,—N(CH₃)—. They represent the mutual connection of fragments A1 to A3 andA1′ to A3′ of bridges B1 and B2.

In a particular embodiment, the organic molecules according to theinvention have a structure of Formula XVIII.

In the donor region, the emitter molecule has an aromatic amine group.The acceptor moiety is a dicyanophenyl group in which twoCN-substituents may be ortho, meta or para to each other and may beadjacent to a bridged aliphatic group.

Q1 to Q6 are each independently selected from the group consisting of H,CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, phenyl, tolyl, xylyl, benzyl,thienyl, oxazolyl, oxadiazolyl, triazolyl, tetrazolyl, oxazolyl,oxadiazolyl, furyl, and carbazolyl.

Q1 and Q2, Q3 and Q4, and Q5 and Q6 may be linked together to form acycloalkyl- or aromatic spiro system (e.g., to stabilize the molecularstructure).

Alk1 to Alk10 are H or a straight-chain or branched-chain(C_(n)H_(2n+1); n=1, 2, 3, 4, 5, or 6) aliphatic group or a cycloalkylgroup (C_(n)H_(2n+1); n=5 or 6), independently of one another.

In addition, Alk1 and Alk6 can be omitted and the two benzene rings ofthe donor system are covalently bonded together to form a carbazoleunit, as shown in Formula XIX.

The formula XVIII illustrates the substituent.

EMBODIMENTS

The molecules in the following examples of the present invention mayhave at least one substitutions of Cl, Br and/or I to increasespin-orbit coupling (SBK). The appropriate position for substitutionscan be determined by quantum mechanical calculations, and acomputational program including SBK (eg, ADF, ORCA program) is usedherein. To know the trend, DFT or CC2 calculation can be conducted, soas to identify the substitution position of halogen, i.e. the halogenatom orbitals with a significant proportion in HOMO, HOMO-1, HOMO-2and/or LUMO, LUMO+1, LUMO+2. For the substitution pattern identified bythis way, it should be noted that, for example, when calculated by TDDFTor CC2, the energy difference ΔE (S₁−T₁) of organic molecules betweenthe lowest excited singlet state (S₁) and it below triplet state (T₁) isless than 2,000 cm-¹, in particular less than 1500 cm-¹, preferably lessthan 800 cm-¹, more preferably less than 400 cm-¹ and most preferablyless than 200 cm-¹.

The materials in the present invention can be synthesized usingcatalytic coupling reactions (e.g. Suzuki coupling reactions,Buchwald-Hartwig cross-coupling reactions) or various condensationreactions that are known to those skilled in the art.

Embodiment 1

Example Molecule 1

The molecules according to the invention shown in Example 1 would bedetailed below. As shown from the frontier orbital in FIG. 3, the HOMOand LUMO were located in distinctly different spatial regions of themolecule. It was expected that the gap between the lowest triplet stateand the singlet state above it was small enough that the moleculeexhibited a significant TADF effect. The calculation of the examplemolecule 1 within the range of TD-DFT calculation (function B3LYP, basisset 6-31G (d, p)) showed that the energy level difference of theoptimized triplet-state geometrical structure was ΔE(S₁−T₁)=75 cm-¹.Therefore, the example molecule 1 was a good TADF emitter. The followingreaction scheme illustrated the chemical synthesis of example molecule1:

Reactants and reaction conditions:

(1) (t-C₄H₉—C₆H₅)₂NH, Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, (CH₃)₃CONa, 90° C., 19hours.(2) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours.

Synthesis can be performed according to the following detailed reactionscheme:

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours(2) HPO₂, I₂, red phosphorus, CH₃COOH, 80° C., 24 hours(3) (H₃PO₄)n, 175° C., 5 hours(4) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(5) (t-C₄H₉—C₆H₅)₂NH, Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, (CH₃)₃CONa, 90° C., 19hours(6) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours

Chemical Analysis:

R_(f)(cyclohexane/ethyl acetate 10:1): 0.52. ¹H NMR (CDCl₃, 300 MHz, δppm): 1.31 (s, 18H), 3.13 (m, 4H), 4.05 (s, 2H), 6.84 (dd, J=3.6 Hz,J=12.0 Hz, 1H), 6.90 (s, 1H), 6.95 (s, 1H), 6.95 (d, J=9 Hz, 5H), 7.22(d, J=9 Hz, 4H), 7.55 (s, 2H). 13C-NMR (300 MHz CDCl₃, δ ppm): 30.72(CH2), 31.46 (CH3), 32.80 (CH2), 34.31 (CH2), 40.56 (Cquat), 113.16(Cquat), 113.73 (Cquat), 115.59 (Cquat), 122.35 (Cquat), 123.48 (CH),123.78 (CqUat), 126.03 (CH), 130.57 (CqUat), 130.94 (CH), 133.86 (CH),134.48 (CH), 136.63 (Cquat), 144.91 (CqUat), 145.40 (Cquat), 145.69(Cquat), 146.31 (Cquat).

MS (ES-MS=electrospray ionization mass spectrometry) m/z: 523 (M⁺). MS(HR-ES-MS=high resolution electrospray ionization mass spectrometer)m/z: C₃₇H₃₇N₃ Calculation: 523.2979, Measurement: 523.2980 (M+).C₃₇H₃₇N₃ Calculation: C 84.86, H 7.12, N 8.02%, Measurement: C 84.54, H7.36, N 7.90%.

The example molecule 1 could be dissolved in many organic solvents suchas methylene chloride (CH₂Cl₂), toluene, hexane, n-octane,tetrahydrofuran (THF), acetone, dimethylformamide (DMF), acetonitrile,ethyl alcohol, methanol, xylene or benzene. The excellent solubility inmethylene chloride made polymethylmethacrylate (PMMA) or polystyrene(PS) doping possible.

The emitter material according to Embodiment 1 could be sublimated(temperature 170° C., pressure 10-³ mbar).

Photophysical measurements of example molecule 1 in PMMA or PS (dopingconcentration c≈1 wt %) demonstrated the occurrence of TADF and thefavorable emission properties. At very low temperatures, for examplewhen T=2K, thermal activation was not possible. Thus, the emissionshowed two very different decay times, namely, a very short component,which corresponded to an S₁→S₀-fluorescence transition, about 4 ns inPMMA, 25 ns in PS, and a very long component, which was classified asphosphorescence of T₁→S₀ transitions, τ(phos)≈550 ms in PMMA andτ(phos)≈450 ms in PS. (Note: nitrogen purging of samples)

FIG. 4 showed the corresponding time-resolved emission spectra in PS,i.e. no delay time (t=0 ns), detection time window Δt=100 ns,corresponding to short-term spectra of fluorescence, and correspondingto the long-term spectra of phosphorescence (t=500 and Δt=900 ms).

When the temperature rose to T=300K, drastic changes in spectra anddecay behavior may occur, which would support the occurrence of TADF.FIG. 5 showed the short time domain (spontaneous fluorescence) and longtime domain time-resolved emission spectra of example molecule 1dissolved in PS. Since both spectra had approximately the same peakpositions, long-lived components could also be interpreted asfluorescence-TADF emission in this case. The fluorescence decay time inPMMA was about 4 ns, and the fluorescence decay time in PS was about 25ns. However, in PMMA, its long-lived component was greatly shortened toabout 10 μs, and the long-lived component in PS was also shortened toabout 10 μs.

It was of significance to compare the emission quantum efficiency atT=300K with the value obtained in ambient air under nitrogen purging(PMMA-doped samples). pL (nitrogen)=40%, pL (air)=25%. The result showedthat the triplet state was involved in the emission process, becauseoxygen in the air usually only caused quenching of long-lived tripletstates (A. M. Prokhorov et al, J. Am. Chem. Soc. 2014, 136, 9637). Sincetriplet state occupation was a prerequisite for generating TADF, thisbehavior again showed that example molecule 1 had the desired TADFproperties. Notes: The emission maximum in PMMA at T=300K within theblue-white range was λ(max)=486 nm (CIE x: 0.198, y: 0.287), and theemission maximum in PS at T=300K within the blue range was λ(max)=450 nm(CIE x: 0.174; y: 0.154).

When studying substances dissolved in toluene, other photophysicalproperties of the emitter molecule according to Embodiment 1 can beidentified. This further demonstrated that, for a simple measurement ofthe emitted quantum efficiency, as mentioned above, it was expected thatthe molecules dissolved in the toluene produced TADF because theemission quantum efficiency in air was significantly reduced. Thecorresponding measured values: Ø_(PL)(nitrogen)=30% and Ø_(PL)(air)=5%.

FIGS. 6a and 6b showed the emission attenuation behavior at T=300K inthe ns region (FIG. 6a ) and the μs region (FIG. 6b ). Spontaneousfluorescence decayed with τ(fluorine)=60 ns. (FIG. 6a ) In addition,there were two attenuation components of τ(TADF 1)=270 ns and τ(TADF2)=9 μs. Both components were classified as TADF emissions.

FIG. 7 showed the time resolved emission spectra of example molecule 1dissolved in toluene in three time domains, namely, the short timedomain (spontaneous fluorescence) and two long time domains. Thesespectra were given of the attenuation components as shown in FIG. 6.Since all three spectra had the same peak position and the same spectralshape within the measurement accuracy range, the long-lived componentcould also be interpreted as fluorescence, i.e. two TADF emissions.

If the study was carried out in the non-phase-change temperature rangeof toluene and the sample that was remained liquid, the attenuationbehaviors of the long-lived components emitted from example molecule 1(concentration c≈10-⁵ mol/l) dissolved in toluene could be obtained. Atemperature range of about 200K to 300K was very suitable. The measuredvalues of the corresponding attenuation components were shown asArrhenius diagrams (Boltzmann diagrams) in FIG. 8. Using Equation 2,Equation 3 could be approximated as the experimentally derived emissiondecay time τ_(exp) (see C. Baleizao, M. N. Berberan-Santos, J. Chem.Phys, 2007, 126, 204510):

$\begin{matrix}{{\ln \left( \frac{1}{\tau_{\exp}} \right)} = {A - \frac{\Delta \; {E_{1}\left( {S_{1} - T_{i}} \right)}}{k_{B}T}}} & (3)\end{matrix}$

Where, A was a constant, i represented the TADF process 1 with ΔE1activation energy in triplet state T₁ or TADF process 2 with activationenergy ΔE2 in triplet state T₂.

The linear fitting of two time domain measurement points, ie two TADFemissions, was performed using Equation 3 according to FIG. 6. From theslope of the straight line, the activation energy could be obtained(ΔE[(S₁−T₁), TADF1]=310 cm-¹ and ΔE [(S₁-T₂), TADF2]=85 cm-¹).

When cooled to T=77K, the long-lived unstructured emissions was frozen.There was only one structured phosphorescence, the decay time was verylong, τ(phos)=450 ms (not shown in the figure). However, for long-livedcomponents, the structure of the spectrum could also be observed in FIG.4. This spectral structure could be attributed to the emission of donoror acceptor fragments. No charge transfer (CT) transition was involvedin this case. If it is assumed that the correlation 0-0 transition atthe intersection of the energetic (extrapolated) sides of the emissioncurve is reflected by the abscissa, these spectra could be used toroughly estimate the energy difference associated with the occurrence ofTADF. The result was that the ΔE was about (300±100) cm-¹, which alsoshowed that the embodiment 1 was a TADF substance.

Therefore, the experiment demonstrated that the example molecule 1produced TADF according to invention. The corresponding results of TADFbehaviors for example molecule 1 doped in PMMA were also available.

It should be emphasized that this also showed that the energy difference75 cm-¹ calculated for the CT transitions (see the description of FIG.3) was very consistent with the activation energy of TADF 2 processdetermined in the experiments.

FIG. 9 schematically summarized the measurement results in a formalenergy level diagram. The emission behavior of example molecule 1 wasdescribed by three excitation energy states. There was another tripletstate T1 (Lok) that could be assigned to local emission under two CTstates 5₁ (CT) and T₂ (CT) with an experimentally determined energydifference of 85 cm⁻¹. The S₁ (CT) state showed transient spontaneousfluorescence and two emissions of long decay time but differenttime-lasting at room temperature, which were generated from the thermalactivation of T₂ (CT) and T₁ (lok), respectively, thus representingdifferent TADF emissions. The formal model described here was based onlong-lived TADF components longer than 9 μs for the relaxation processbetween triplet states.

Here also illustrated one aspect for the naming of triplet state. It wasbased on the numbering by energy order, rather than by the type ofelectron excitation. Therefore, in the case of example molecule 1, theenergy gap ΔE (S₁−T₁) between the CT states used was referred to as ΔE[S₁(CT)−T₂(CT)] due to the generation of the state T₁(Iok) of lowenergy.

Embodiment 2

Example Molecule 2

The example molecule 2 according to the invention would be detailedbelow. As shown from the frontier orbital in FIG. 10, the HOMO and LUMOwere located in distinctly different spatial regions of the molecule. Itwas expected that the gap between the lowest triplet state and thesinglet state above it was small enough that the molecule exhibited asignificant TADF effect. The calculation of the example molecule 2within the range of TD-DFT calculation (function B3LYP, basis set 6-31G(d, p)) showed that the energy level difference of the optimizedtriplet-state geometrical structure was ΔE(S₁−T₁)=85 cm-¹. Therefore,the example molecule 2 was a good TADF emitter. The following reactionscheme illustrated the chemical synthesis of example molecule 2.

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours(2) HPO₂, 1₂, red phosphorus, CH₃COOH, 80° C., 24 hours(3) (H₃PO₄)n, 175° C., 5 hours(4) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(5) (t-C₄H₉—C₆H₅)₂NH, Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, (CH₃)₃CONa, 90° C., 19hours(6) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours

Embodiment 3

Example Molecule 3

The molecules according to the invention shown in Embodiment 3 would bedetailed below. As shown from the frontier orbital in FIG. 11, the HOMOand LUMO were located in distinctly different spatial regions of themolecule. It was expected that the gap between the lowest triplet stateand the singlet state above it was small enough that the moleculeexhibited a significant TADF effect. The calculation of the examplemolecule 3 within the range of TD-DFT calculation (function B3LYP, basisset 6-31G (d, p)) showed that the energy level difference of theoptimized triplet-state geometrical structure was ΔE (S₁−T₁)=55 cm-¹.Therefore, the example molecule 3 was a good TADF emitter.

The following reaction scheme illustrated the chemical synthesis ofexample molecule 3.

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours.(2) HPO₂, I₂, red phosphorus, CH₃COOH, 80° C., 24 hours(3) (H₃PO₄)n, 175° C., 5 hours(4) (C₂H₅)₂O, 30° C., 24 hours NH₄Cl, H₂O; F₃CCO₂H, 3 hours, 50° C.(5) Carbazole, Pd(CH₃COO)₂, P[(C(CH₃)₃]₃, (CH₃)₃CONa, 90° C., 19 hours(6) K₄ [Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH3)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140°C., 12 hours

Embodiment 4

Example Molecule 4

The example molecule 4 according to the invention would be detailedbelow. As shown from the frontier orbital in FIG. 12, the HOMO and LUMOwere located in distinctly different spatial regions of the molecule. Itwas expected that the gap between the lowest triplet state and thesinglet state above it was small enough that the molecule exhibited asignificant TADF effect. The calculation of the example molecule 4within the range of TD-DFT calculation (function B3LYP, basis set 6-31G(d, p)) showed that the energy level difference of the optimizedtriplet-state geometrical structure was ΔE(S₁−T₁)=88 cm-¹. Therefore,the example molecule 4 was a good TADF emitter.

The following reaction scheme illustrated the chemical synthesis ofexample molecule 4.

Reactants and reaction conditions

(1) CH₃CO₂Na, 230° C., 3 hours(2) HPO₂, I₂, red phosphorus, CH₃COOH, 80° C., 24 hours(3) (H₃PO₄)_(n), 175° C., 5 hours(4) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(5) (t-C₄H₉—C₆H₅)₂NH, Pd(CH₃COO)₂, P[(C(CH3)₃]₃, (CH₃)₃CONa, 90° C., 19hours(6) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH3)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours

Embodiment 5

Example Molecule 5

The example molecule 5 according to the invention would be detailedbelow. As shown from the frontier orbital in FIG. 13, the HOMO and LUMOwere located in distinctly different spatial regions of the molecule. Itwas expected that the gap between the lowest triplet state and thesinglet state above it was small enough that the molecule exhibited asignificant TADF effect. The calculation of the example molecule 5within the range of TD-DFT calculation (function B3LYP, basis set 6-31G(d, p)) showed that the energy level difference of the optimizedtriplet-state geometrical structure was ΔE(S₁−T₁)=150 cm-¹. Therefore,the example molecule 5 was a good TADF emitter. The following reactionscheme illustrated the chemical synthesis of example molecule 5.

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours(2) HPO₂, I₂, red phosphorus, CH₃COOH, 80° C., 24 hours(3) (H₃PO₄)_(n), 175° C., 5 hours(4) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(5) (t-C₄H₉—C₆H₅)₂NH, Pd(CH₃COO)₂, P[(C(CH3)₃]₃, (CH₃)₃CONa, 90° C., 19hours(6) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH3)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours

Embodiment 6

Example Molecule 6

The example molecule 6 according to the invention would be detailedbelow. As shown from the frontier orbital in FIG. 14, the HOMO and LUMOwere located in distinctly different spatial regions of the molecule. Itwas expected that the gap between the lowest triplet state and thesinglet state above it was small enough that the molecule exhibited asignificant TADF effect. The calculation of the example molecule 6within the range of TD-DFT calculation (function B3LYP, basis set 6-31G(d, p)) showed that the energy level difference of the optimizedtriplet-state geometrical structure was ΔE(S₁−T₁)=30 cm-¹. Therefore,the example molecule 6 was a good TADF emitter.

Embodiment 7

Example Molecule 7

FIG. 15 showed the frontier orbitals HOMO and LUMO of example molecule7. Since these orbitals were located in distinctly different spatialregions of the molecule, it could be expected that the gap between thelowest triplet state and the singlet state above it was small enoughthat the molecule exhibited a significant TADF effect. The calculationof the example molecule 7 within the range of TD-DFT calculation(function B3LYP, basis set 6-31G (d, p)) showed that the energy leveldifference of the optimized triplet-state geometrical structure wasΔE(S₁−T₁)=550 cm-¹. Therefore, the example molecule 7 was a good TADFemitter.

The following reaction scheme illustrated the chemical synthesis ofexample molecule 7.

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours(2) HI (57% aqueous solution), red phosphorus, 80° C., 24 hours(3) (H₃PO₄)_(n), 175° C., 5 hours(4) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(5) (CH₃)₂NH, Pd (CH₃COO)₂, P[(C(CH₃)₃]₃, (CH₃)₃CONa, 90° C., 19 hours

Embodiment 8

Example Molecule 8

As shown from the frontier orbitals in FIG. 16, the HOMO and LUMO werelocated in distinctly different spatial regions of the molecule. It wasexpected that the gap between the lowest triplet state and the singletstate above it was small enough that the molecule exhibited asignificant TADF effect. The calculation of the example molecule 8within the range of TD-DFT calculation (function B3LYP, basis set 6-31G(d, p)) showed that the energy level difference of the optimizedtriplet-state geometrical structure was ΔE(S₁−T₁)=540 cm-¹. Therefore,the example molecule 8 was a good TADF emitter.

The following reaction scheme illustrated the chemical synthesis ofexample molecule 8.

Reactants and reaction conditions:

(1) CH₃CO₂Na, 230° C., 3 hours(2) HI (57% aqueous solution), red phosphorus, 80° C., 24 hours(3) CH₂N₂, SO₂Cl₂, 80° C., 2 hours; (CH₃)₃COH, C₆H₅COOAg, Et₃N, 90° C.,2 hours(4) (H₃PO₄)_(n), 175° C., 5 hours(5) Al[OCH(CH₃)₂]₃, 275° C., 3 hours(6) (CH₃)₂NH, Pd(CH₃COO)₂, P[(C(CH3)₃]₃, (CH₃)₃CONa, 90° C., 19 hours(7) K₄[Fe(CN)₆], Pd(CH₃COO)₂, P[(C(CH3)₃]₃, Na₂CO₃, (CH₃)₂NCHO, 140° C.,12 hours

Embodiment 9

Example Molecule 9

FIG. 17 showed the frontier orbitals HOMO and LUMO of example molecule9. Since these orbitals were located in distinctly different spatialregions of the molecule, it could be expected that the gap between thelowest triplet state and the singlet state above it was small enoughthat the molecule exhibited a significant TADF effect. The calculationof the example molecule 9 within the range of TD-DFT calculation(function B3LYP, basis set 6-31G (d, p)) showed that the energy leveldifference of the optimized triplet-state geometrical structure wasΔE(S₁−T₁)=550 cm-¹. Therefore, the example molecule 9 was a good TADFemitter.

Embodiment 10

Example Molecule 10

FIG. 18 showed the frontier orbitals HOMO and LUMO of example molecule10. Since these orbitals were located in distinctly different spatialregions of the molecule, it could be expected that the gap between thelowest triplet state and the singlet state above it was small enoughthat the molecule exhibited a significant TADF effect. The calculationof the example molecule 10 within the range of TD-DFT calculation(function B3LYP, basis set 6-31G (d, p)) showed that the energy leveldifference of the optimized triplet-state geometrical structure wasΔE(S₁−T₁)=140 cm-¹. Therefore, the example molecule 10 was a good TADFemitter.

Embodiment 11

Example Molecule 11

FIG. 19 showed the frontier orbitals HOMO and LUMO of example molecule11. Since these orbitals were located in distinctly different spatialregions of the molecule, it could be expected that the gap between thelowest triplet state and the singlet state above it was small enoughthat the molecule exhibited a significant TADF effect. The calculationof the example molecule 11 within the range of TD-DFT calculation(function B3LYP, basis set 6-31G (d, p)) showed that the energy leveldifference of the optimized triplet-state geometrical structure wasΔE(S₁−T₁)=420 cm-¹. Therefore, the example molecule 11 was a good TADFemitter.

Embodiment 12

Example Molecule 12

FIG. 20 showed the frontier orbitals HOMO and LUMO of example molecule12. Since these orbitals were located in distinctly different spatialregions of the molecule, it could be expected that the gap between thelowest triplet state and the singlet state above it was small enoughthat the molecule exhibited a significant TADF effect. The calculationof the example molecule 12 within the range of TD-DFT calculation(function B3LYP, basis set 6-31G (d, p)) showed that the energy leveldifference of the optimized triplet-state geometrical structure wasΔE(S₁−T₁)=1250 cm-¹. Therefore, the example molecule 12 was a good TADFemitter.

FIG. 21 showed other example molecules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of the energy level of the thermallyactivated delayed fluorescence (TADF) process. k_(B)T represents thermalenergy with a Boltzmann constant k_(B) and an absolute temperature T.This figure shows both the radiative and non-radiative (marked by wavylines) attenuation processes of the radiation TADF process and thelow-temperature observable T₁ state. The figure does not mark thespontaneous S₁→S₀ fluorescence process.

FIG. 2 shows a schematic diagram of orbital energies of molecules withdonor fragments and receptor fragments (D-A molecules) according to thepresent invention. Due to non-conjugated bridges, the interactionbetween the donor and acceptor tracks is small. Thus, the electronicproperties of the D and A fragments can be approximated separately, thatis, the D orbital energy is approximately equal to the energy of thecorresponding free (unlinked) donor molecule, and the A orbital energyis approximately equal to the energy of the corresponding free(unlinked) acceptor molecule. The HOMO energy of the isolated donor(electron-rich) is significantly higher than HOMO energy of the isolatedacceptor (electron-deficient). The LUMO of an isolated donor is muchhigher than the LUMO energy of an acceptor. Therefore, the HOMO of theD-A molecule is mainly located on the D fragment, while the LUMO of theD-A molecule is mainly located on the A fragment.

FIG. 3 shows an isosurface of the frontier orbital of the examplemolecule 1 (see Embodiment 1), HOMO: left, LUMO: right. The electronicground state S₀ geometry is optimized. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The calculation result showed that the energy differencebetween the singlet state-CT state and the triplet state-CT state is 75cm-¹ (S₀-geometry). This value indicates that the example molecule 1 isa good TADF emitter.

FIG. 4 shows time-resolved emission spectra of example molecule 1 dopedabout 1% by weight in PS at T=2K. Record the short-term spectrum in caseof no time delay (t=0 ns) and detection time window Δ1 t=100 ns andrecord the long-term spectrum in case of a time delay t=500 μs (timewindow Δt=900 ms). Excitation: short-time spectrum: 375 nm, pulse width70 ps; long-time spectrum, excitation: 365 nm, pulse width: 10 ns.

FIG. 5 shows time-resolved emission spectra and decay time τ of examplemolecule 1 doped about 1% by weight in PS at T=300K. Record theshort-term spectrum in case of no time delay (t=0 ns) and detection timewindow Δt=100 ns and record the long-term spectrum in case of a timedelay t=1 μs (time window Δt=100 μs). Excitation: short-time spectrum:375 nm, pulse width 70 ps; long-time spectrum, excitation: 355 nm, pulsewidth: 2.9 ns.

FIG. 6 shows the emission decay behaviors of example substance 1dissolved in toluene, (a) short time domain (spontaneous fluorescence)and (b) long time domain, T=300K. Record the spontaneous fluorescenceemission decay time τ(fluorescence)=60n and TADF decay time τ(TADF1)=270 ns and τ(TADF 2)=9 μs of respective components. Introducenitrogen for 120 min to degas the solution. Excitation wavelength: 355nm, pulse duration: 2.9 ns, and concentration: about 10-⁵ mol/l.

FIG. 7 shows the time-resolved emission spectra of example molecule 1 ata concentration of 10-⁵ M dissolved in toluene when T=300K. Record (a)short-time spectra (spontaneous fluorescence) of no time delay (t=0 ns)and test time window Δt=50 ns, (b) long-term spectrum (TADF1) with timedelay t=300 μs (time window Δt=600 ns) and (c) long time spectrum(TADF2) with time delay t=5 μs (time window Δt=30 μs). Excitation:Short-time spectrum: 375 nm, pulse width 70 ps, long-time spectrum,excitation: 355 nm, pulse width: 2.9 ns.

FIG. 8 shows the Boltzmann diagram (Arrhenius diagram) of long-livedcomposition of the corresponding emission decay time of example molecule1 dissolved in toluene according to equation 3. The activation energyΔE(S₁−T₁)=(310±10)cm-¹ and ΔE(S₁−T₂)=(85±5)cm⁻¹ obtained by fitting. TheT1 state is the local state, and the T2 is classified as the chargedonor transfer state.

FIG. 9 shows the formal energy level diagram, used to schematicallydescribe the experimental emission decay time and activation energy.T₁(lok) represents the local state, while T₂(CT) and S₁(CT) representthe charge transfer state. The heat returns from T₁(lok) and T₂(CT) tothe S₁(CT) state, resulting in two TADF processes.

FIG. 10 shows an isosurface of the frontier orbital of the examplemolecule 2 (see Embodiment 2), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=85 cm-¹ Both values indicate thatexample molecule 2 is a good TADF emitter.

FIG. 11 shows an isosurface of the frontier orbital of the examplemolecule 3 (see Embodiment 3), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=55 cm-¹ The result indicates thatexample molecule 3 is a good TADF emitter.

FIG. 12 shows an isosurface of the frontier orbital of the examplemolecule 4 (see Embodiment 4), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=88 cm-¹ The result indicates thatexample molecule 4 is a good TADF emitter.

FIG. 13 shows an isosurface of the frontier orbital of the examplemolecule 5 (see Embodiment 5), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=150 cm-¹ The result indicates thatexample molecule 5 is a good TADF emitter.

FIG. 14 shows an isosurface of the frontier orbital of the examplemolecule 6 (see Embodiment 6), HOMO: left, LUMO: right. Optimization ofthe electron ground state S₀ and the lowest triplet state T₁ geometry.Calculation method: DFT and TD-DFT, function: B3LYP, basis set: 6-31G(d, p), calculation software: Gaussian 09. The result: ΔE(S₁−T₁)=35 cm-¹(S₀-geometry) and 30 cm⁻¹ (T₁-geometry). Both values indicate thatexample molecule 2 is a good TADF emitter.

FIG. 15 shows an isosurface of the frontier orbital of the examplemolecule 7 (see Embodiment 7), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=550 cm-¹ The result indicates thatexample molecule 7 is a good TADF emitter.

FIG. 16 shows an isosurface of the frontier orbital of the examplemolecule 8 (see Embodiment 8), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T, geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=540 cm-¹ (T, geometry) The resultindicates that example molecule 8 is a good TADF emitter.

FIG. 17 shows an isosurface of the frontier orbital of the examplemolecule 9 (see Embodiment 9), HOMO: left, LUMO: right. Optimization ofthe lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=550 cm⁻¹ (T₁-geometry) The resultindicates that example molecule 9 is a good TADF emitter.

FIG. 18 shows an isosurface of the frontier orbital of the examplemolecule 10 (see Embodiment 10), HOMO: left, LUMO: right. Optimizationof the electron ground state geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=140 cm-¹ The result indicates thatexample molecule 10 is a good TADF emitter.

FIG. 19 shows an isosurface of the frontier orbital of the examplemolecule 11 (see Embodiment 11), HOMO: left, LUMO: right. Optimizationof the electron T₁ state geometry. Calculation method: DFT and TD-DFT,function: B3LYP, basis set: 6-31G (d, p), calculation software: Gaussian09. The result: ΔE(S₁−T₁)=420 cm⁻¹ The result indicates that examplemolecule 11 is a good TADF emitter.

FIG. 20 shows an isosurface of the frontier orbital of the examplemolecule 12 (see Embodiment 12), HOMO: left, LUMO: right. Optimizationof the lowest triplet state T₁ geometry. Calculation method: DFT andTD-DFT, function: B3LYP, basis set: 6-31G (d, p), calculation software:Gaussian 09. The result: ΔE(S₁−T₁)=1250 cm-¹ (T₁ geometry) The resultindicates that example molecule 12 is a good TADF emitter.

FIG. 21 shows schematic representation of other molecules according tothe invention.

1. An organic molecule for luminescence, in particular for use as aluminophore in optoelectronic devices, comprising or consisting of astructure of the formula I,

Receptor A is an aromatic or heteraromatic chemical group, the HOMO islocated on the group and the group optionally has at least onesubstitution; Bridge B1, bridge B2 connect organic groups of the donor Dand acceptor A in a non-conjugated manner.
 2. The organic moleculeaccording to claim 1, wherein the donor D and/or the acceptor A are eachselected from aromatic or heteroaromatic groups of the formulas II andIII,

wherein the molecular fragments of the donor D and the acceptor A aredifferent, wherein the formula II and/or formula III are optionally partof a fused ring system, having # positions, and the donor D and acceptorA are linked to the bridge B1 and bridge B2 via the positions, and Y1,Y2, Y3 and Y4 are independently selected from C and N; X1 to X7 areindependently selected from N, O, S, SE, CH, NH, C—R1 and N—R2; whereinR1 and R2 groups are each independently selected from —H, alkyl(particularly methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, adamantyl), cycloalkyi (particularly cyclopropyl,cyclopentyl, cyclohexyl), alkenyl (particularly vinyl, allyl), alkynyl(particularly ethynyl), aryl (particularly phenyl, tolyl, naphthyl),heteroaryl (particularly furyl, thienyl, pyrrolyl), chemicallysubstituted alkyl, alkenyl, alkynyl, aryl, or heteroaryl, alkoxy (—OR′),thioalkyl (—SR′), sulfonyl (—SO₂R′), acyl (—COR′), formyl (—CHO),carboxyl (—CO₂R′), boryl (—BR′R″), sulfinyl (—SOR′), amine (—NR′R″),phosphino (—PR′R″), phosphinyl (—POR′R″), amido (—NR′COR″), silyl(—SiR′R″R′″), cyano and (—CN), nitro (—NO₂), nitroso (—NO), isocyanato(—NCO), thiocyano (—NCS) or halogen (—F, —Cl, —Br, —I); wherein R1 andR2 of the fragments X1 to X3 and X4 to X7 are optionally linked to eachother in such a way as to form an additional aliphatic, aromatic orheteroaromatic ring system; wherein the residues R′, R″, and R′″ aredefined as R1 and R2, wherein the residues R′, R″, and R′″ areoptionally linked to each other in such a way as to form an additionalaliphatic, aromatic or heteroaromatic ring system.
 3. The organicmolecule according to claim 2, wherein the groups R1 and R2 areindependently selected from alkyl-C_(n)H_(n+1) (1≤n≤8, particularly1≤n≤4), cycloalkyl-CnH2n−1 (3≤n≤6), substituted alkyl/cycloalkyl,alkoxy-OC_(n)H_(n+1) (1≤n≤8), thioalkyl-SC_(n)H_(n+1) (3≤n≤6), oralkylated amine groups, —N(C_(n)H_(2n+1))(C_(n′)H_(2n′+1)) (n and n′=1to 8) or —N(C_(n″)H2_(n″−1))(Cn′″H2n′″−1) (n″ and n′″=3, 4, 5 or 6),wherein n is an integer respectively.
 4. The organic molecule accordingto claim 1, wherein the donor D has at least one substituent and thesubstituent is independently selected from —O, —NH-alkyl, —N— (alkyl)₂,—NH₂, —OH, —O—NH (CO)-alkyl, —O (CO)-alkyl, alkyl, aryl, heterocyclyl,—(CH)═C-alkyl, phenothiazinyl, phenoxathiazinyl, carbazolyl,dihydrophenazinyl, —N(R′) (R″), wherein all aryl and heterocyclyl groupsare optionally substituted by alkyl and/or aryl groups, wherein allalkyl groups are also optionally substituted by F, Cl, Br and/or I;wherein R′, R″═H, alkyl, aryl, haloalkyl or haloaryl.
 5. The organicmolecule according to claim 1, wherein the acceptor A has at least onesubstituent and the substituent is selected from halogen, —(CO) H,—(CO)-alkyl, —(CO) OH, —(CO) Cl, —CF₃, —BF₂, —CN, —S(O)₂OH,—S(O)₂O-alkyl, —NH₃ ⁺, —N(R′)(R″)(R′″)⁺, —NO₂, haloalkyl and —B(R′)(R″);wherein R′, R″═H, alkyl, aryl, haloalkyl or haloaryl.
 6. The organicmolecule according to claim 1, comprising at least one Cl, Br and/or Iatom(s), in particular for increasing spin orbit coupling.
 7. Theorganic molecule according to claim 1, wherein the bridges B1 and B2independently of one another have a structure according to one of theformulas IV and V:

wherein # is labeled as a linking site of the donor D or acceptor A ofthe molecule with other groups; A1 is selected from

O, S and

wherein R3-R7 are each independently selected from —H, alkyl(particularly methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, adamantyl), cycloalkyi (particularly cyclopropyl,cyclopentyl, cyclohexyl), alkenyl (particularly vinyl, allyl), alkynyl(particularly ethynyl), aryl (particularly phenyl, tolyl, naphthyl),heteroaryl (particularly furyl, thienyl, pyrrolyl), chemicallysubstituted alkyl, alkenyl, alkynyl, aryl, or heteroaryl, alkoxy (—OR′),thioalkyl (—SR′), sulfonyl (—SO₂R′), acyl (—COR′), formyl (—CHO),carboxyl (—CO₂R′), boryl (—BR′R″), sulfinyl (—SOR′), amine (—NR′R″),phosphino (—PR′R″), phosphinyl (—POR′R″), amido (—NR′COR″), silyl(—SiR′R″R′″), cyano and (—CN), nitro (—NO₂), nitroso (—NO), isocyanato(—NCO), thiocyano (—NCS) or halogen (—F, —Cl, —Br, —I), where R′, R″,and R′″ are each have the same definition as R1 or R2; Chemical groupsA2 and A3 are: A2 is selected from

O, S and

A3 is selected from

S and

wherein one or more of the chemical groups A2 to A3 are optionallyselected from

wherein R8 to R22 are are each independently selected from —H, alkyl(particularly methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, adamantyl), cycloalkyi (particularly cyclopropyl,cyclopentyl, cyclohexyl), alkenyl (particularly vinyl, allyl), alkynyl(particularly ethynyl), aryl (particularly phenyl, tolyl, naphthyl),heteroaryl (particularly furyl, thienyl, pyrrolyl), chemicallysubstituted alkyl, alkenyl, alkynyl, aryl, or heteroaryl, alkoxy (—OR′),thioalkyl (—SR′), sulfonyl (—SO₂R′), acyl (—COR′), formyl (—CHO),carboxyl (—CO₂R′), boryl (—BR′R″), sulfinyl (—SOR′), amine (—NR′R″),phosphino (—PR′R″), phosphinyl (—POR′R″), amido (—NR′COR″), silyl(—SiR′R″R′″), cyano and (—CN), nitro (—NO₂), nitroso (—NO), isocyanato(—NCO), thiocyano (—NCS) or halogen (—F, —Cl, —Br, —I), where R′, R″,and R′″ are each have the same definition as R1 or R2, and wherein thebridges B1 and B2 link the donor D or acceptor A and in the presence ofA2 to A3 according to formula V, the groups of formula V are linked toeach other via atoms C, Si, O, S, N, P, B or Ge.
 8. The organic moleculeaccording to claim 7, comprising or consisting of a structure selectedfrom formulas VI to XVII

wherein Y1′-Y4′ are defined as Y1-Y4; X1′-X7′ are defined as X1-X7; A1′,A2′ and A3′ are defined as A1 to A3; Z, a chemical group for linking thefragments A1 to A3 of the bridges B1 and B2 to one another, is selectedfrom —CH₂—, —C(CH₃)₂—, —O—, —C₆H₄ (phenylene) —C₅H₈-(Cyclopentyl), —CO—(carbonyl), —SO₂— and —N(CH₃)—; wherein Y1-Y4 and X1-X7 are eachindependently selected from —H, alkyl (particularly methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, adamantyl),cycloalkyi (particularly cyclopropyl, cyclopentyl, cyclohexyl), alkenyl(particularly vinyl, allyl), alkynyl (particularly ethynyl), aryl(particularly phenyl, tolyl, naphthyl), heteroaryl (particularly furyl,thienyl, pyrrolyl), chemically substituted alkyl, alkenyl, alkynyl,aryl, or heteroaryl, alkoxy (—OR′), thioalkyl (—SR′), sulfonyl (—SO₂R′),acyl (—COR′), formyl (—CHO), carboxyl (—CO₂R′), boryl (—BR′R″), sulfinyl(—SOR′), amine (—NR′R″), phosphino (—PR′R″), phosphinyl (—POR′R″), amido(—NR′COR″), silyl (—SiR′R″R′″), cyano and (—CN), nitro (—NO₂), nitroso(—NO), isocyanato (—NCO), thiocyano (—NCS) or halogen (—F, —Cl, —Br,—I), where R′, R″, and R′″ are each have the same definition as R1 orR2.
 9. The organic molecule according to claim 1, comprising a structureaccording to formula XVIII or consisting of a structure according toformula XVIII,

wherein, Q1 to Q6 are each independently selected from H, CH₃, C₂H₅,C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, phenyl, tolyl, xylyl, benzyl, thienyl,pyrazolyl, diazolyl, triazolyl, tetrazolyl, oxazolyl, oxadiazolyl,furyl, and carbazolyl; wherein Q1 and Q2, Q3 and Q4, and Q5 and Q6 areoptionally linked, thereby forming a cycloalkyl system or an aromaticspirocyclic system; Alk1 to Alk10 are, independently of each other, H oran unbranched or branched aliphatic group or a cycloalkyl group.
 10. Theorganic molecule according to claim 1, comprising one structureaccording to formula XIX or consisting of a structure according toformula XIX,

wherein Q1, Q2, Q3, Q4, Q5, and Q6 are each independently selected fromH, CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, phenyl, tolyl, xylyl, benzyl,thienyl, pyrazolyl, diazolyl, triazolyl, tetrazolyl, oxazolyl,oxadiazolyl, furyl, and carbazolyl; wherein Q1 and Q2, Q3 and Q4, and Q5and Q6 are optionally linked, thereby forming a cycloalkyl system or anaromatic spirocyclic system; Alk2, Alk3, Alk4, Alk5, Alk7, Alk8, Alk9,and Alk10 are, independently of each other, H or an unbranched orbranched aliphatic group or a cycloalkyl group.
 11. Applications of theorganic molecule according to claim 1 in a light-emitting device,especially in an emitter layer of optoelectronic device, and inparticular, in organic light-emitting diodes (OLEDs).
 12. A method formanufacturing optoelectronic devices, wherein the molecules according toclaim 1 are used.
 13. An optoelectronic device, having the moleculesaccording to claim
 1. 14. The organic molecules according to claim 1wherein the optoelectronic device is selected from an organiclight-emitting diode (OLED), a light emitting electrochemical cell (LEECor LEC), an OLED sensor, especially an unsealed shielded gas and vaporsensor, an optical temperature sensor, an organic solar cell (OSC), anorganic field effect transistor, an organic laser, an organic diode, anorganic photodiode and a “down-conversion” system.